Explosively driven fragment launcher and a method for explosively launching a fragment at a target

ABSTRACT

Disclosed techniques relate to fragment launching. In an example, a fragment launcher has a casing, a launch aperture and a detonation position. An inner profile of the casing tapers from the main body towards the fragment launch aperture and from the main body to the detonation position. A fragment is held within the launch aperture such that when in use an explosive charge can be initiated to launch the fragment from the launcher. The launcher is particularly suited to uses where there is a requirement to launch a fragment in a consistent and repeatable manner.

TECHNICAL FIELD OF THE INVENTION

This invention relates to the field of fragmentation launchers andparticularly to the design of an explosively driven fragment launcherand a method for explosively launching a fragment at a target.

BACKGROUND TO THE INVENTION

There is a requirement to ensure that armours utilised in the protectionof personnel and platforms are produced to rigorous standards, furtherto this there is also a requirement to ensure that the munitionsproduced also meet the required safety and manufacturing standardsincluding those standards relating to insensitive munitions, which setrequirements on how the munition should behave when damaged, includingdamage caused from fragmentation. The testing of these systems needs tobe completed in a controlled manner to ensure that the materials inquestion are rigorously tested to the appropriate standard. Theseassessments typically require a projectile or fragment, or fragments tobe ‘fired’ or launched at a target. The target is then assessed fordamage using a variety of known methods including visual inspection,X-Ray or any other destructive or non-destructive method. In these testregimes it is critical that the projectile or fragments arrives at thetarget at the appropriate speed or velocity, whilst also being of theappropriate shape, volume or cross sectional area, i.e. avoidingdeformation or oblation. It is also important to try to minimise anycollateral effects attributable to the launch method which may obfuscatethe effects on the target from the projectile or fragment under test.Furthermore it is also vital that the test method and apparatus are ableto achieve the desired effects consistently and repeatedly.

Existing test systems can be expensive and complex to produce in acontrolled way to allow for repeatable and consistent test results.Furthermore, in order to achieve the higher velocities (>1500 ms⁻¹) forlarger size fragments (>50 g) using a device such as an explosivelydriven fragment launcher, the amount of explosive required, alsoreferred to as Net Explosive Quantity (NEQ), makes it difficult tooperate within the safety constraints of some test ranges or facilities.In addition increasing the amount of explosive increases the chances ofproducing unwanted fragmentation of the confinement casing, unless theconfinement casing is made substantially thicker, which again has animpact on cost and ease of production.

As such there is a requirement for a fragment launching device, which iscapable of delivering a range of velocities for a range of fragmentsizes, weights or volumes, whilst also minimising the amount ofexplosive material required, thus increasing the safety aspects of use.

Therefore it is an aim of the present invention to provide analternative explosively driven fragment launcher and method forexplosively launching a fragment at a target.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided anexplosively driven fragment launcher comprising a casing, having a mainbody for housing an explosive charge, the casing further comprising afirst end provided with a launching aperture configured to hold afragment and a second end provided with a detonation position configuredto receive a detonation means for detonating the explosive charge,wherein the inner profile of the casing tapers from the main bodytowards the launching aperture and from the main body towards thedetonation position, such that in use an explosive pressure is directedtowards a fragment to be launched.

Armour systems for vehicles or personnel must be appropriately tested toensure they meet the stringent standards and requirements placed uponthem. These protection systems must be tested in numerousconfigurations, dependent on how they are expected to be used, forexample on a person, within a vehicle or within an installation such asa bunker or as part of wider infrastructure such as buildings. Thisleads to tests being required on various material types as well as aplurality of variations for example thickness. Similar tests are alsorequired for munition casings where there is a requirement to ensurethat the casing can withstand impacts from projectiles or fragmentswithout compromising the integrity of the weapon, this can extendfurther to storage containers or boxes for such munitions. Furthermoreas well as this variety of test targets there are numerous weapons andeffects which need to be simulated. For example a bullet may be used totest a specific armour however this may also be simulated through theuse of a surrogate projectile. In the instance of testing armour ormunitions casings it may be preferable to test using a projectile tosimulate fragmentation from weapons systems, where this is the case theprojectile may be referred to as a fragment. This testing requires thatprojectiles or fragments of a plurality of sizes, volumes and weightscan be launched to specific velocities in a controlled and repeatablemanner. To achieve this a fragment launcher may be used, consisting of ameans to hold the fragment and a launching means. In the case of anexplosively driven fragment launcher, the launching means is anexplosive material contained within a body of the launcher. Theexplosive material is detonated such that the explosive pressure wavesor gases act upon the fragment imparting energy such that the fragmentor projectile is launched. The velocity of the fragment is determined byits mass and the amount of energy imparted from the explosive pressurewaves or gas. As such the velocity is typically related to the amount ofexplosive material used, where increasing the amount of explosivematerial would increase the velocity of the fragment. This relationshipis often described using the Gurney equations or similar.

The inventor has identified improvements to an explosively drivenfragment launcher to enable cost effective and efficient delivery ofhigh speed fragments of a plurality of sizes, shapes and weights, withrelatively low amounts of explosive material, also referred to as NetExplosive Quantity (NEQ).

The explosively driven fragment launcher has an outer casing with a mainbody for housing an explosive charge comprising a first end and a secondend. In this context the first end is that which would be directedtowards and closest to, the ‘target’. The ‘target’ is simply thematerial which would receive the fragment or projectile after launch andmay take many forms, such as a witness plate, armour panel, sheetmaterial, munition casing or ammunition box or container, test standardsincluding those which may be biofidelic, or any other such object. Thesecond end is that which is directed away from and furthest from the‘target’. The first end is provided with a launching aperture configuredfor holding a fragment or projectile of a plurality of shapes, sizes andweights. The aperture provides a channel from the outside of the casingto the internal volume, and is preferably positioned central to thelongitudinal axis of the fragment launcher. This aperture can be anythree dimensional shape, but preferably is shaped to match thedimensions and shape of the fragment. For example it may provide arecess suitable for a fragment cuboid in shape, furthermore where thecross sectional area of this cuboid is varied between fragments theaperture can also be altered to accommodate such variations in fragmentsize. Additionally should a cylindrical or spherical fragment orprojectile be used the aperture can equally be manufactured toaccommodate those three dimensional shapes, or any conceivable alternateshape. Advantageously the aperture may be manufactured such that it isconformal to the fragment, such that there is a close fit between thetwo. This advantageously ensures that the explosively formed gases donot bleed or leak around the fragment thus ensuring efficient transferof energy from the explosive pressure to the fragment. The aperture canbe of uniform cross section through the first end of the casing,connecting the outer external surface and inner volume of the casing.Alternatively it can have a varied cross section or profile, as anexample a ‘stepped profile’ with the outermost section of the first endof the casing aperture being of a depth and cross-sectional areasuitable for housing the fragment or projectile and any additional depthof outer casing toward the internal volume of the casing, being of adifferent cross sectional area. For example a reduced cross sectionalarea could be used to provide a ‘seat’ for the fragment to assistlocating the fragment in the aperture, as well as providing means forfurther focusing of the explosively formed pressure or gases from withinthe casing main body behind the fragment.

Alternatively the launch aperture may be provided with an adjustableholding mechanism, such as a chuck, such that the size of launchaperture can be adjusted to accommodate fragments of different crosssections. The chuck may reduce the cross sectional area using any knowncommon configuration, for example for a cylindrical geometry the chuckwould provide the ability to hold fragments of different diameter. Thechuck may be adjusted using a tool or key which interfaces with thechuck mechanism, alternatively a ‘tool free’ adjustment mechanism may bebuilt in which allows for adjustment by hand. The mechanism adjusts theclamping elements such as to provide an aperture for the fragment ofvariable cross section. The chuck advantageously allows for anadjustable fragment holder which provides sufficiently conformal fittingsuch as to hold the fragment, whilst still allowing efficient launch ofthe fragment.

Alternatively, instead of modifying the launch aperture to becomplementary to the fragment, the inventor has shown that fragments canbe manufactured such as to have a standard outer shape or cross sectionbut may contain a fragment of an alternative shape, size or volumewithin it. For example, a standard sized disc “blank” may be used tocreate a fragment of a given shape and thickness, by cutting, machiningor perforating the desired fragment shape, for example a cuboid, intothe surface of the disc. Sufficient material is removed such that priorto use the disc is partially perforated such that the fragment remainsattached to the disc, but in use the same said perforations provide aweakness such that the explosive pressure or gases causes the desiredfragment to part, in this example the cuboid, from the disc and istherefore launched. This advantageously allows for the launch apertureto be manufactured to standard dimensions simplifying the manufacturingprocess of the launcher, whilst still providing the ability to launchfragments of a range of preselected masses, shapes and sizes.

The second end of the casing is provided with a detonation positionconfigured to receive detonation means. The detonation position providesa channel from the outside of the casing to the internal volumeconfigured to receive a detonation means, and is preferably positionedcentral to the longitudinal axis of the fragment launcher. This channelcan be varied in size or shape or both, for example for a channel with acircular cross-sectional area when viewing the invention in plan view,the diameter could be varied to accommodate detonation means ofdiffering diameters. Alternatively for a channel with a squarecross-sectional area, this area could as equally be varied. Furthermorethe detonation position can be manufactured to receive a detonationmeans with a plurality of fixing methods. For example the detonationmeans may be mounted using a friction fit where the detonation means isa tight fit with the detonation position. Alternatively the detonationmeans may be fixed by threaded means, where both the casing anddetonation means are threaded such that they can be fixedly attached,this advantageously provides a robust connection able to withstand theblast pressures generated in use. The detonation means can be chosenfrom any of the well know methods within the art and may also includedevices referred to as initiators. These may be electrical ornon-electrical detonation means designed to safely initiate anexplosive.

The main body of the casing is the remaining casing between the firstend and second end, and is configured such as to have an internal volumesuitable for receiving an explosive charge. This explosive charge can beany explosive materials known to the art, but preferably a malleable ormouldable explosive such as plastic explosive. It is the detonation ofthis explosive charge which in turn creates the explosive pressure andgases which are directed toward and launch the fragment from the launchaperture.

The casing internal volume tapers from the main body internal walltowards the launching aperture at the first end. This taperingadvantageously allows for the directing of the explosive pressure towardfragment via the launch aperture. This tapering may be stepped orpreferably smooth to provide predictable performance of the propagationof the explosive wave pressures or gases within the casing. The taperingmay be formed by known manufacturing techniques such as milling,machining or casting or advanced or additive manufacture. The taperingmay take any shape, for example, when viewed in cross-section throughthe plan view of the invention, it may reduce linearly or non-linearly,taking a convex or concave profile. The position of the start of thetapering of the internal section is determined by profile or angle ofsuch profile and as such can be varied to provide a plurality ofinternal shapes or curvatures to the tapering. The tapering of the mainbody towards the first end is terminated by the fragment launchaperture. Furthermore the casing internal volume tapers from the mainbody internal wall towards the detonation position at the second end.This tapering may be stepped or preferably smooth to provide predictableperformance of the movement of the explosive pressure or shock wavethrough the explosive material within the casing. The tapering towardsthe second end also advantageously allows for the shaping of theexplosive material, held within the main body of the casing, which inturn creates a shaped detonation charge, which advantageously directsthe explosive shock wave and gases towards the launch aperture. Thetapering may be formed by known manufacturing techniques such asmilling, machining or casting or advanced or additive manufacture. Thetapering may take any shape, for example, when viewed in cross sectionthrough the plan view of the invention, it may reduce linearly ornon-linearly, taking a convex or concave profile. The position of thestart of the tapering of the internal section is determined by therequired profile or angle of such profile and as such can be varied toprovide a plurality of internal shapes or curvatures to the tapering.The tapering of the main body towards the second end is terminated bythe detonation position.

The outer casing should be of suitable thickness to safely contain theexplosive material when in use, but may be varied, for example tominimise cost, for example to produce a single use device. Alternativelythe casing may provide suitable containment to the explosive such thatit may be reused. The outer casing may be made of any suitable materialwhich provides sufficient strength suitable for the confinement of theinternally held explosive charge when in use. The material selected mustalso be able to be manufactured to have the desired internal tapering,fragment launch aperture at the first end and detonation position at thesecond end. A typical material may be a metal or alloy for examplesteel, but other materials such as plastics or composites may also provesuitable. The casing may be formed using any known manufacturing ormachining technique such as forming, milling or turning, additionally itmay be formed by additive or advanced manufacturing processes.

In certain embodiments of the invention the first end comprises a capremovably attached to the main body. The cap may be configured such thatit contains the launch aperture, additionally it may also be configuredto contain all or part of the internal tapering from the main bodytowards the launch aperture. The cap may be configured to anypredetermined proportion of the main body casing. Advantageously thisprovides access to the internal volume of the invention whilstadditionally providing a simple means to modify the launch aperture bothin terms of shape or size, with a further advantage of providing a meansto modify a proportion of, or all of the tapering from the main body tothe launch aperture. The material of the cap may be selected to be thesame material as the outer casing, alternatively it may also be selectedfrom any suitable alternative material to that of the main casing. Atypical material may be a metal or alloy for example steel, but othermaterials such as plastics or composites may also prove suitable. Thecap may be removably attached using any known means suitable to thematerials of the cap and outer casing, such as fasteners, clamps,brackets, in addition to other known fixing methods such as frictionfitting or use of a bonding material or media.

In further embodiments of the invention the second end comprises a capremovably attached to the main body. The cap may be configured such thatit contains the detonation position, additionally it may also beconfigured to contain all or part of the internal tapering from the mainbody towards the detonation position. The cap may be configured to anypredetermined proportion of the main body casing. Advantageously thisprovides access to the internal volume of the invention whilstadditionally providing a simple means to modify the detonation positionboth in terms of shape or size, with a further advantage of providing ameans to modify a proportion of, or all of the tapering from the mainbody to the launch aperture. The material of the cap may be selected tobe the same material as the outer casing, alternatively it may also beselected from any suitable alternative material to that of the maincasing. A typical material may be a metal or alloy for example steel,but other materials such as plastics or composites may also provesuitable. The cap may be removably attached using any known meanssuitable to the materials of the cap and outer casing, such asfasteners, clamps, brackets, in addition to other known fixing methodssuch as friction fitting or use of a bonding material or media.

In certain embodiments of the invention the cap(s) is or are removablyattached to the main body section by threaded means. The threaded meanscan be manufactured using any known machining or manufacturingtechnique. Advantageously the threading means provides for a simplemethod for both attaching and removing the removably attached cap(s). Anadditional advantage is that in use, the threaded means is able towithstand the forces of the blast pressure wave ensuring that theexplosively driven fragment launcher remains intact, further improvingthe safety of device.

In certain embodiments of the invention there is a spacer with a firstand second end, configured to reduce the internal volume of the mainbody section, wherein there is a channel between the first and secondend of said spacer. Within this context the first end is that which isclosest to the launch aperture and the second end is that which isclosest the detonation position. The spacer may be selected from apreselected set of sizes, shapes or volumes and is placed internal tothe main body casing such as to vary and reduce the internal volume ofthe main body casing. This advantageously allows for a configurableexplosively driven fragment launcher wherein by varying the internalvolume the amount of explosive charge is also varied, resulting in anexplosive pressure wave which can be optimised to the fragment size ormass as well as to the required fragment velocity. An additionaladvantage is that the configurability is provided within the samephysical main body casing without the requirement of having tomanufacture multiple casings of different size or internal volume thusreducing both manufacturing complexity as well as cost. The inventor hasfurther identified that the use of spacer internal to the main bodycasing, as opposed to simply reducing the volume of explosive charge andleaving a void, improves the transfer energy to the fragment from theexplosive blast wave, thus making a more reliable and predictablefragment launching device whilst also achieving higher velocities thenotherwise might be possible. The channel between the first and secondend of the spacer is configured to allow for the explosive gas orpressure wave to travel unobstructed towards the first end of thedevice, namely that containing the launch aperture, additionally helpingto concentrate the gases or shockwave. As well as the spacer size orvolume being able to be varied, advantageously the channel size may alsobe varied, for example if the spacer is viewed in cross-section thecross-sectional area of the channel could be varied, allowing furthercontrol of the explosive gases or shock wave. The spacer may bepositioned within the main body of the casing at any position betweenthe casing first end and the casing second end. Preferably the spacer ispositioned internal to the main body casing at the first end, such thatthe first end of the spacer is adjacent the launch aperture. Thisadvantageously allows for the explosive material to be placed betweenthe spacer second end and the main casing second end. Even morepreferably the spacer may be placed adjacent the main casing second endadjacent the detonation position. Advantageously this allows for theexplosive material or fill to be adjacent the launch aperture. When inthis position the channel within the spacer may also be furtherconfigured to accept or propagate an initiation shock wave from thedetonation means or provide a detonation position for the detonationmeans. The spacer can be made of any suitable material andadvantageously can be selected to be the same or different to that ofthe main body casing. The material can be selected such that the spaceris reusable such that in use, it is able to withstand the forces andpressures associated with the explosive blast, alternatively it may beselected such that the material breaks or fails, such that the spacer isa single use item. A typical material for the spacer may be a metal oralloy for example steel, but other materials such as plastics orcomposites may also prove suitable. Plastic is a general term whichincludes a variety of polymeric materials. The material may be selectedfrom any of these known materials. The use of a plastic materialadvantageously allows for a simple and cost effective manufacturingprocess to be used. Additionally plastic materials lend themselves to beshaped easily allowing for various shapes and sizes to be produced tosuit the requirement of the invention. The shaping of the spacer may beformed using any known manufacturing or machining technique such asforming, milling or turning, additionally it may be formed by additiveor advanced manufacturing processes, which include techniques commonlyreferred to as ‘3D printing’.

In certain embodiments the plastic material may be AcrylonitrileButadiene Styrene (ABS). The inventor has shown that this material issimple to manufacture to the desired shape of the spacer, for exampleusing additive manufacture, is cost effective and furthermore withstandsthe forces experienced when in use.

In further embodiments of the invention the first and second end of thespacer are shaped substantially to match the internal tapering of themain body. The inventor has identified that this shaping advantageouslyincreases the efficiency, reliability and repeatability of the fragmentlauncher.

In this context ‘shaped to match’ means that either or both the firstand second end of the spacer are shaped so as to be complimentary to thefirst or second end of the internal tapering of the main body casing. Incertain embodiments of the invention the spacer first end may be shapedto substantially match the inner tapering of the casing first end, suchthat if the spacer was inserted in the casing internal volume within thefirst end, the spacer would be conformal to any tapering towards thelaunch aperture. Preferably the spacer may have the second end shaped tosubstantially match the internal tapering of the second end of the mainbody casing, such that if the spacer was inserted in the casing internalvolume it would be conformal to any tapering towards the detonationposition. Even more preferably the spacer may have the second end shapedto substantially match the internal tapering of the second end of themain body casing, such that if the spacer was inserted in the casinginternal volume it would be conformal to any tapering towards thedetonation position, and furthermore the spacer first end is also shapedto be complementary to the shape of the second end of the spacer. Theinventor has shown that this advantageously allows for efficient energytransfer through the explosive charge towards the launch aperture. Theshaping of the spacer may be formed using any known manufacturing ormachining technique such as forming, milling or turning, additionally itmay be formed by additive or advanced manufacturing processes whichinclude techniques commonly referred to as ‘3D printing’.

In further embodiments of the invention the internal tapering of themain body casing towards the detonation position is between 10 and 70degrees to the longitudinal axis of the casing. This range of anglesshould also be considered to include those angles within typicalmanufacturing tolerances. Positive angles are measured clockwise fromthe longitudinal axis of the invention which is at zero degrees. Theinventor has shown this range of angles advantageously allow forefficient transfer of energy or gases from the explosive material to thefragment, such that for a reduced explosive fill the required velocitiesmay be achieved for a given fragment mass.

In further embodiments of the invention the internal tapering of themain body casing towards the launching aperture is between 10 and 70degrees to the longitudinal axis of the casing. This range of anglesshould also be considered to include those angles within typicalmanufacturing tolerances. The inventor has shown this range of anglesadvantageously allow for efficient transfer of energy or gases from theexplosive material to the fragment, such that for a reduced explosivefill the required velocities may be achieved for a given fragment mass.

In certain embodiments of the invention the angle of the internaltapering of the main body casing towards the launching aperture iscomplementary to that of the internal tapering of the main body casingtowards the detonator position. This advantageously allows for efficientenergy transfer to the fragment, whilst additionally providing thebenefit of simplifying manufacture.

In further embodiments of the invention the angle of the internaltapering is 30 degrees to the longitudinal axis of the casing. Thisangle should also be considered to include those angles within typicalmanufacturing tolerances. The inventor has shown that this angleadvantageously provides for the efficient transfer of energy, both interms of the propagation of the explosive shock wave through theexplosive material but also in then focusing or imparting said energyonto the fragment in the launch aperture.

In certain embodiments the explosively driven fragment launcher theouter casing is cylindrical, the internal tapering of the main bodytowards the launching aperture and from the main body towards thedetonation position is conical. This geometry has been shown to beadvantageous in producing a predictable and repeatable performance. Ithas been further shown to provide a launcher with the requiredperformance in an easy to manufacture form.

In further embodiments of the invention there is an explosive chargewithin the main body of the casing. This advantageously means that thelauncher can be provided ‘ready to use’ and such that the explosivefilling is undertaken in the correct controlled environment by anappropriate person or authority.

According to a second aspect of the invention there is provided a methodof explosively launching a fragment comprising the steps of, providingan explosively driven fragment launcher in accordance with the firstaspect of the invention, providing an explosive charge, position theexplosively driven fragment launcher a predetermined distance from thetarget with the launching aperture aimed at said target, inserting afragment of predetermined size into the launching aperture, inserting adetonation means into the detonation position, initiating the detonationmeans such that an explosive pressure wave is initiated, such that thefragment is explosively launched at the target. This methodadvantageously achieves repeatable launch velocities for a givenfragment size or mass, utilising lower amounts of explosive whencompared to other methods for launching fragments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross-sectional view of an embodiment of theexplosively driven fragment launcher;

FIG. 2 a illustrates cross-sectional view of an alternative embodimentof the explosively driven fragment launcher; and

FIG. 2 b illustrates an exploded view of the embodiment of FIG. 2 a.

DETAILED DESCRIPTION

FIG. 1 shows a cross-sectional view of one embodiment of the explosivelydriven fragment launcher 100, through the longitudinal axis 120, thatwhich passes symmetrically through the centre of the launcher. Thelauncher having a cylindrical main body casing 101 machined from mildsteel such that three sides of the internal volume are formed. At thefirst end 102 there is a removably attached cap 103. This cap 103 ismachined from the same mild steel as the main body casing 101 andattached using a threaded means (not shown) such that the main bodycasing 101 and cap 103 have complimentary threads. Furthermore the cap103 has been machined with an internal conical tapering 104 towards thelaunch aperture 105 at an angle of 30 degrees to the longitudinal 120.The launch aperture 105, recessed into the end cap 103, is machined tobe complimentary to the shape of the fragment (not shown), such that thefragment remains in position through friction fit. The second end 106shows the internal conical tapering 107 towards the detonation position108 at an angle of 30 degrees to the longitudinal axis. The detonationposition receives the detonation means (not shown). Within the main bodycasing 101 the explosive charge 109 is shown conformal to the internaltapering 107 of the second end 106. In use the detonation means (notshown) detonates or initiates the explosive charge 109 which in turngenerates an explosive shockwave or gases which propagate towards thelaunch aperture 105 at the first end 102. The internal tapering 104towards the launch aperture 105 focus the explosive energy onto thefragment (not shown) held in the launch aperture 105, the gases orexplosive shockwave then launch the fragment at a target (not shown).

FIG. 2 a shows a cross-sectional view of a second embodiment of theexplosively driven fragment launcher 200, through the longitudinal axis,that which passes symmetrically through the centre of the launcher. Thelauncher having a cylindrical main body casing 201 machined from mildsteel such that three sides of the internal volume are formed. At thefirst end 202 there is a removably attached cap 203. This cap 203 ismachined from the same mild steel as the main body casing 201 andattached using a threaded means (not shown) such that the main bodycasing 201 and cap 203 have complimentary threads. Furthermore the cap203 has been machined with an internal conical tapering 204 towards thelaunch aperture 205 at an angle of 30 degrees to the longitudinal axis220. The launch aperture 205, recessed into the end cap 203, is machinedto be complimentary to the shape of the fragment (not shown), such thatthe fragment remains in position through friction fit. The main bodycasing second end 206 shows the internal conical tapering 207 towardsthe detonation position 208 at an angle of 30 degrees to thelongitudinal axis 220. The detonation position 208 receives thedetonation means (not shown). Within the main body casing 201 the spacer209 is illustrated with a first end 210 with conical tapering at 30degrees to the longitudinal axis, such as to complement the shape of thespacer second end 211. The figure further shows the spacer second end211 conformal to the main body casing 201 internal conical tapering 207.The spacer has a channel 212 which runs from the detonation position 208through to the explosive charge 213. The explosive charge 213 is shownconformal to the internal volume of the main body casing 201 and thespacer first end 210. In use the detonation means (not shown) detonatesor initiates the explosive charge 213 which in turn generates anexplosive shockwave or gases which propagate towards the launch aperture205 at the first end 202. The internal conical tapering 204 towards thelaunch aperture 205 focus the explosive energy onto the fragment (notshown) held in the launch aperture 205, the gases or explosive shockwavethen launch the fragment at a target (not shown).

FIG. 2 b shows an exploded view of the fragment launcher 200, withcylindrical main body casing 201 made of mild steel, a first end 202with removably attached cap 203, also made of mild steel with launchaperture 205, shaped to receive the fragment 214. The fragment 214 hasbeen machined such that in use a cuboid fragment is launched. The figurefurther illustrates the spacer 209 made of plastic with conical taperingand the explosive charge 213, shaped to complement the shape of thespacer 209.

1. An explosively driven fragment launcher comprising a casing having amain body for housing an explosive charge, the casing further comprisinga first end provided with a launching aperture configured to hold afragment and a second end provided with a detonation position configuredto receive a detonation means for detonating the explosive charge,wherein an inner profile of the casing tapers from the main body towardsthe launching aperture and from the main body towards the detonationposition, such that in use an explosive pressure is directed towards afragment to be launched.
 2. The explosively driven fragment launcher ofclaim 1, wherein the first end comprises a cap removably attached to themain body,
 3. The explosively driven fragment launcher of claim 1,wherein the second end comprises a cap removably attached to the mainbody.
 4. The explosively driven fragment launcher of claim 2, whereinthe cap is removably attached to the main body by threaded means.
 5. Theexplosively driven fragment launcher of claim 1, further comprising aspacer with a first and second end, configured to reduce an internalvolume of the main body, wherein there is a channel between the firstand second end of said spacer.
 6. The explosively driven fragmentlauncher of claim 5, wherein either or both the first and second end ofthe spacer is or are shaped substantially to match an internal taperingof the main body.
 7. The explosively driven fragment launcher of claim6, wherein the spacer comprises a plastic material.
 8. The explosivelydriven fragment launcher of claim 6, wherein the internal tapering ofthe main body casing towards the detonation position is between 10 and70 degrees to a central longitudinal axis of the casing.
 9. Theexplosively driven fragment launcher of claim 8, wherein an internaltapering of the main body casing towards the launching aperture isbetween 10 and 70 degrees to the central longitudinal axis of thecasing.
 10. The explosively driven fragment launcher of claim 1, whereinan angle of the internal tapering of the main body casing towards thelaunching aperture is complementary to that of the internal tapering ofthe main body casing towards the detonator position.
 11. The explosivelydriven fragment launcher of claim 8, wherein an angle of the internaltapering is 30 degrees to the central longitudinal axis of the casing.12. The explosively driven fragment launcher of claim 6, wherein anouter casing is cylindrical, the internal tapering of the main bodytowards the launching aperture and from the main body towards thedetonation position is conical.
 13. The explosively driven fragmentlauncher claim 1, comprising an explosive charge within the main body ofthe casing.
 14. An armour test apparatus comprising the fragmentlauncher of claim
 1. 15. A method of explosively launching a fragment ata target comprising the steps of: a. providing an explosively drivenfragment launcher according to claim 1; b. providing an explosive chargewithin the main body of the casing; c. positioning the explosivelydriven fragment launcher a predetermined distance from the target withthe launching aperture aimed at said target; d. inserting a fragment ofpredetermined size into the launching aperture; e. inserting adetonation means into the detonation position; and f. initiating thedetonation means such that an explosive pressure wave is initiated, suchthat the fragment is explosively launched at the target.